LUNG-EXPANSION TECHNIQUES

 LUNG-EXPANSION TECHNIQUES A lung-expansion technique is any technique that increases lung volume or assists the patient in increasing lung volume above that reached at his or her usual unassisted or uncoached inspi- ration. Rationales for the use of various strategies to promote lung inflation include

 (a) to increase pulmonary compliance. (

b) to increase partial arterial pressure of oxygen (Pao2). (

c) to decrease work of breathing. and 

(d) to increase removal ofsecreions . 

Lung-expansion techniques are meant to duplicate a normal sigh maneuver . Theoretically. sighs or periodic hyperinflations to near-total lung capacity reverse microatelectasis . Lung-expansion techniques are indicated to prevent atelectasis and pneumonia in patients who cannot or will not take periodic hyperinflations (94], such as postoperative upper- abdominal and thoracic surgical patients and patients with respi- ratory disorders due to neuromuscular and chest wall diseases. Adequately performed. maximum inspirations 10 times each hour while awake significantly decrease the incidence of pul- monary complications after laparotomy (95). Whatever techniques are used postoperatively (e.g., coached sustained maximal inspiration with cough, incentive spirometry, volume oriented intermittent positive-pressure breathing, intermittent CPAP, or positive expiratory pressure (PEP) mask therapy (961 ) , it should be taught and practiced preoperatively. when properly used, coached sustained maximal inspiration with cough and incentive spirometry—the least expensive and safest techniques—are as effective as any other method [97). Of the several commer- dally available incentive spirometers, the one chosen should combine accuracy, low price, and maximum patient accessibility (981. Because there are no definitive studies comparing the relative efficacy of volume- and flow-oriented incentive spirometers,he choice Of equipment must based on empiric assessment of patient acceptance, eaq• of use, and cost. mien chest Sion with postural drainage is added to the previously mentioned expansion techniques in patients without prior lung disea«•. it has failed to affect the incidence of postoperative pulmonary complications AIRWAY CLEARANCE Efficient mucociliary clearance and effective cough are the two basic processes necessary for normal clearance of the airways. In abnormal situations, this system may be dysfunctional and lead to mucus retention [ 100). A discussion of techniques aimed at enhancing airway clearance follows. 

AUGMENTATION OF MUCOCILIARY CLEARANCE Mucociliary clearance is one of the most important defense mechanisms of the respiratory system. Mucociliary dysfunction is any defect in the ciliary and secretory elements of mucocil- iary interaction that disturbs the normal defenses of the airway epithelium [1011. Ineffective mucociliary clearance leads to re- tention of tracheobronchial secretions. Mucociliary clearance may be ineffective 'be rnecti-- anisms or over Copyfish port, or both. Mu